Last year, as Mad Men's superlative fifth season came to a close, a strange woman approached Don Draper as he sat alone in a bar with a simple question: "My friend down there, she was wondering... Are you alone?" As Don turned to answer, the scene cut to black, leaving every viewer to contemplate the question for themselves.

And now, at the start of Mad Men's sixth season, we finally have our answer: "Midway in our life's journey, I went astray from the straight road, and woke to find myself alone in a dark wood," reads Don Draper, quoting Dante's Inferno at the outset of tonight's "The Doorway." A 14th-century epic poem that chronicles a trip to Hell isn't your typical beach read, but it's an apt and tone-setting choice for this strange, affecting episode of Mad Men, which sets a course for an equally strange and affecting season.

"The Doorway" splits its time between four characters — Don, Betty, Roger, and Peggy — in the stretch from Christmas to New Year's Eve. Don continues to coast on his name and reputation at Sterling Cooper Draper Pryce as Megan's acting career begins to take off. Betty mentors a talented young friend of Sally's and takes an unexpected trip to a flop house in Greenwich Village. Roger splits his time between his therapist's couch and his mother's funeral, though he refuses to acknowledge the seriousness of either. Peggy handles a potential crisis with a client at her new firm and proves herself, for better or worse, a true Draper protege.

But this episode wasn't really about Don, Betty, Roger, or Peggy. It was about death. This is not a new idea for Mad Men, which, on a thematic level, is nearly as obsessed with death as was Six Feet Under — a show that was literally set in a funeral home. Every episode of Mad Men begins with the unsubtle image of a character falling from a building for a reason. But if death was Mad Men's barely concealed subtext before, "The Doorway" pummels you with it for two hours to make sure you're getting the message. It's not just the near-death experience of the doorman Jonesy, which Don weirdly and obsessively fixates on, or Roger's mother's funeral; even a character as unassuming as Bobby Draper has death on the brain as he compares a violin case to a coffin.

But as much as "The Doorway" sees characters confronting their inevitable ends — whenever they may come — this is also an episode of Mad Men that's obsessed with the show's past. At their New Year's Eve party in tonight's premiere, Don and Megan break out Kodak's Carousel, which Don so memorably immortalized in Mad Men's first season finale. "In Greek, nostalgia literally means 'the pain from an old wound,'" explained Don at the time, and he has accumulated plenty of wounds since then, most of them self-inflicted. So it's no great surprise when we learn that Don is having an affair with his neighbor Sylvia. As Don wrote in Mad Men's fourth season, during a rare moment of clarity, "People tell you who they are, but we ignore it, because we want them to be who we want them to be." Though we spent the entire fifth season watching Don deny his baser instincts, the very first episode of Mad Men in its debut season told us exactly who Don Draper is — which probably won't change, no matter how much we viewers might want him to be someone different.

And it's that very darkness that Don has come to epitomize, which we see once more when he finally presents his big, splashy ad campaign for a Hawaiian hotel. The ad depicts a discarded suit and tie alongside footprints leading into the ocean. Don's clients and colleagues immediately realize that the subtext of the ad is that the disrobed mystery man has committed suicide. Don, however, leaves the meeting puzzled by the suggestion.

Whether he admits it or not, the truth is that Don always knew that the ad was about death. Much earlier in the series, we saw Don himself strip off his suit and wander into the ocean, in season two's "The Mountain King" — and if that moment was supposed to symbolize his rebirth, his "experience" in Hawaii gave him no such similar illusions about second chances. As Don is dragged, drunk, into his apartment building in the middle of "The Doorway," he pesters Jonesy about what he saw during his near-death experience, despite the doorman's obvious discomfort with the subject. When Jonesy reluctantly confesses that there was "a light," Don immediately compares it to "hot tropical sunshine" and "the ocean," recalling his own strangely morbid trip to Hawaii. Mad Men, in its sixth season, is poised to continue exploring that dark tunnel — but based on this episode, there's no guarantee of light at the end.